Coupling arrangement for use in wave transmission systems



D. H. RING COUPLING ARRANGEMENT FOR USE IN WAVE TRANSMISSION SYSTEMS Filed Bed. 51, 1942 Q March 2, 1948;

- r0 BALANCING, Nsrwomr 0F TRANS; our/ ur BEA TING OSC/LL A TOR T0 nun/o TRANSMITTER i of ANTENNA ourpur 4550mm er TRANSMITTER IMPEDANCE INPUT INVENTOR D. H RING 2.! 5 ATTORNEY SHIFT 4 /a0 PHASE 0; TRANS. our/=07 r0 rRANsM/rr/Nc a RECEIVING ANTENNA SIGNAL INPUT i 0F OUTPUT FROM ANTENNA NO ourpqr mew TRANSMITTER 0 m AV n 0C Patented Mar. 2, 1948 COUPLING ARRANGEMENT FOR USE IN a WAVE TRANSMISSIONHSYSTEMS Douglas H. Ring, Red Bank, N. J-., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y.,' a corporationof New York Application December 31, 1942, Serial No. 470,812

4 can... (01; 250-20) This invention relates to wave transmission systems and particularly to coupling arrangements for use in such systems.

An object of the invention is to provide efficient transmission of wave power between certain of a plurality of wave transmission lines or circuits in a wave transmission system while substan tially preventing transmission of wave power between others of them.

Another object is to provide balance in systerns involving wave motion. 575 Q A related object is to provide with simple and economical apparatus an extremely accurate electrical balance between certain parts of a wave transmission network so as to prevent wave transmission therebetween at a given frequency, while allowing efllcient wave transmission between other parts of the network at that frequency."

A more specific object is to so couple-'four transmission lines or'circuits that when wave power is applied to any oneof them, two others of the lines or circuits will receive part of this power while the fourth will receive no power,

These objects are attained in accordance with the invention in the following manner.

A coupling device consisting of a hollow metal wave guide connected in a continuous transmission loop or ring of suitable dimensions is used. The four individual lines or circuits between which wave transmission at a given frequency is to be respectively prevented or allowed, which may be also constructed of hollow metal'wav'e guides, are symmetrically connected as branches to spaced points around the'loop or-ringgin the plane thereof, each by a series electrical connection, i. -e., in the electric plane. The electrical in the wave polarity-in that portion of the loop with respect to the wave polarity in the other three portions of the loop, or by introducing an extra one-half wave-length of line in one of the four portions of the loop so as to provide between each two oppositely situated connections of the branch circuits, two electrical paths around the ring or loop which differ geometrically by a half wave-length.

'The'various objects and features of the invention will be better understood from the following detailed description thereof when read in conjunction with the accompanying drawings in which! I a Fig. 1 shows a perspective view of a coupling arrangement embodying one form of the inven.-

' tion applied to one terminalof a two-way radio characteristics of the portions of the loop or ring connecting each pair' "of oppositely situated branch circuits are made such that when wave power of a given frequency is'applied to the loop from any one of them, the two portions 'of-the wave power transmitted over opposite sides of the loop will be 180' degreesout of 'phase so as to cancel at the point of connection of the oppositely situatedbranch circuit, and thereby preventing transmission of any of the wave power into that branch circuit and allowing transmission of only a part of the wave power into each of the two intermediate branch circuits. This is accomplished in accordance with one embodiment of the invention by making the electrical characteristics ofthe portions of the waveguide loop, connecting each pair of adjacent branch circuits equal except for asuita'ble twist in one of them so as to produce a 180-degree phaseshift communication system; and

' Fig. 2 shows a sectional view of a coupling arrangement embodying another form of the in vention applied to a portion of a double detec-'- tion or superheterodyne signal receiver and Fig. 2A shows a sectional view of a modification of a portion'of the coupling arrangement of Fig. '2 illustrating a third'application of the invention. In Fig. l'the coupling arrangement of the radio terminal of the invention includes four straight sections l, 2, 3 and 4 of hollow metal wave guide with rectangular cross-section connected together so as to form a closed transmission loop. Four straight pieces of hollow metal wave guide also with rectangular cross-section, in the same plane as the wave guide loop, are respectively connected to thefour junctions between the four wave guide sections in the transmission loop symmetrically, i. e., the axis ofeach straight wave guide branch passes throughthe center of the loop. Each wave guide branch is connected electrically in series with the wave guide loop, i. e,, in the electric plane or plane parallel to the lines .of electric intensity in both joined guides;

.. vAs indicated, the branch Wave guide 5 connected to'the junction between the waveguide sections I and 4' of the transmission loop leads to a common antenna for reception and transmission; the branch wave guide 6 connected to the junction between the wave guide sections I and 2 of the coupling loop leads to a radio receiver; the branch wave guide 1 connected to the junction between the wave guide sections -2 and 3 of the coupling loop leads to a balancing network or termination; and the branch wave guide, 8 connected. to the junction between the "a closed ring section along its longitudinal axis being shown,

wave guide sections 3 and 4 of the coupling loop leads to a radio transmitter. I

The wave guide branch 4 of the coupling loop is provided with a suitable twist, as shown, to produce ISO-degree phase shift in the wave polarity in the guide. Except for this, the opposite wave guide sections of-theecoupllngfl'oop, and the junctions of the opposite sections with the branch wave guides are made to have respectively identical electrical characteristics. The-- the electric field polaritiesfori an outgoing wave appliedto the wave. guide loop: from the; transmitte-r connected to branch wave guide?- 8;. and the light line vectors. the electric. field polarities for an incoming. wave applied-to the. loop from the antenna connectedto: wave guide? branch 5, acting as a receiving. antenna. Thenirectiorr of travel of the waves represented by the-vectors is indicated: by the small transverse arrows on the vectors. It will: be noted that for the case where a wave is applied: bythe transmitterto the'wave guide loop through thebranchi-ng wave guide 8, due to the ISO-degree phase shift of'the wave polarity in the: loop branch. 4, the wave portions passing in opposite: directions:- around the wave guide loop arrive: at the junction of: the loop with the branch. wave guide 6;v 180- degrees out of phase so that they; cancel-each other which is equivalent toa; short circuit; at that point. Thus there will be no power flow between sec.- tio'ns- 2 and, I of. the loop dueto:- excitation. from wavev guide branch 8 and nowave. energy" will be applied to: the receiver: connected to the branch guided; whereas the portions: of the wave transmitted over the loop via the paths 4 and 3 will be: absorbed in the wave guide branch -leadlng to: the antenna and the wave guide branch: 1 leading; to the balancing network, respectively.

Similarly, when waves are applied tothe wave guide loop throughthewave guide branch: Efrem the antenna duringv signal reception, the two portions of the applied:v wavepassing around. the wave guide loop in opposite.- direction-s; because of. the: 180-degree relative: phase! shift in wave polarity produced: by the twist in theloop branch 4,. arrive at thejunction. of the: transmission loop with the wave guide branch 1 leading to the with four straight hollow metal wave guide branches H), II, l2 and I3 branching out from it symmetrically, i. e., the axis Of each straight guide passes through the center of the ring, at spaced points around its circumference. Each of the four wave guide branches l0, ll, 12 and l13x is connected to the ring by an equivalent electrical series connection, that is, in the electric plane or plane parallel to the lines of electric intensity of both connected guides. The incoming signals are applied to the input of the branch, wave guide l0, and the beatin oscillator frequency to the input of the branch guide I2,

.andthe; inputs: of1 two detectors are fed respecjunction of. the. ring.

balancing network. in opposite phase relation,

so that there. is no power flow between sections 2. and 3. of. the loop, and no wave energy is transmitted. to the balancing network; whereas the portions of the wave transmitted via paths and 4 are absorbed in the wave guide branches 6 and 8 leading to the receiverand the'transmitter, respectively.

Fig. 2 shows a; modifiedform of coupling" a-rrangement according to the invention used for the purpose of" obtaining-conjugacy between the signal and beating oscillator input to a detectorcircuit in a doubledetecti'on orsuperheterody-ne radio receiving system. In the figure, the coupling arrangement of the invention comprises 9- of hollow metal wave guide, a

tlvely fromtheother two branch guides H and I3 in the manner which will be described below.

A ISO-degree. phase shift in the wave polarity in the electrical" path around one side of the ring between each pair of oppositely situated branch guides with respect to the wave polarity in the otherv electrical path around the other side of the ring between. the same two branch guides is obtained by making the-electrical spacing between two: of. the adjacent. wave guidebranches along the meanv circumferenceof, the ring, such asthe. spacing: between the. wave: guide branches ill and I3, as indicated one-half waverlength longer than.- the electrical. spacing alongthe mean circumference of the ring between each two adjacent. wave guide branches; in v the remaining portion of the ring, which. aremade identical. Thus, the two portions of the signalwave applied tothe waveguidebranch Illa, passing in opposite direetionsaa-round the two sides. of the ring, will the junction of the ring and; the wave guide branch. I2 and willieed substantially equal power intothe; junctions of the; waveguide ring with the, wave guide branchesv H and #3. Also, the two; portions; of the beat; frequency wave; applied to, the wave guide. branch. t2 passing around: the wave guide in opposite directions, will be degrees out of phase; so as to cancel at the with thewave: guide branch l0 and will feed equallyinto; the. junctions of the ring with the wave. guidezbranches. H and t3. Therefore, none of. the; signal energy applied to branch; We will? enter the wave guide branch l2.to which: the. beating. oscillator is connected, and none of the energy of the beating oscillator frequency. applied to the wave guide branch 12' will enter the wave guide branch ID to which the signal input is: connected, whereas the signal energy and the beating." oscillator frequency energy will: be: equally divided between the Wave guide branches, H and I3. The signal and beating oscillator wave energy entering the wave guide: branch I! is takenoff therefrom by means of a transversesection of coaxial line including. a. conductingv wire t4; extending diamametral wire, each coaxial? openings in its; side walls, forming the: inner conductor of the coaxial: conductor" pairs, and two coaxial extensions; l5 and 24 on. either side of the: waveguide branch atboth ends of'the diextension being shortcircuited" by respective: adjustable pistons. I6, IT. A crystal detector I8 is connected: in shunt across the detector alongthe wire- I 4, the circuit being tuned toresonance at the desired frequency by proper adjustment of the position of the piston-s I6 l1. By simultaneous movement of the pistons I 6 and 1 111 the same direction, the impedance-presented to the waves in the guides and thereby the amount of power extracted by the transverse circuit and applied to the detector l8 may be adjusted. The combination products of the beating oscillator frequency and the signal in the output of the detector l8 are impressed upon the filter 19 which selects the intermediate frequency. A similar transverse coaxial line, shunting crystal detector and filter, associated with the branch wave guide l3 provides means for combining the portions of the beating oscillator frequency and the signal diverted into that branch guide to produce waves of intermediate frequency. The intermediate frequency outputs of the two detectors transmitted over the circuits 20 and 2| respectively, are combined in the circuit 22 leading to the second detector stage (not shown) of the receiver in proper phase to add, due to the crossing of the conductors of the circuit 2| at the point 23. The use of the coupling arrangement of the invention in this arrangement has the advantage that the usual signal and beating oscillator filters are eliminated.

In place of the two detectors connected in pushpull, as described, one detector associated with one of the branch wave guides l I, I3 may be used and a suitable matching impedance termination substituted for the detector associated with the opposite Wave guide branch l3, H, as indicated in Fig. 2A. Also, a twist to provide ISO-degree phase shift of the wave polarity in one portion of the wave guide ring between adjacent branch circuits, similar to that illustrated for the loop circuit of Fig. 1, may be employed to produce the desired conjugacy of the wave guide branches to which the signal and beating oscillator inputs are applied, in place of employing-an extra one-half wave-length of line in one branch as illustrated in Fig. 2.

Various modifications of the coupling arrangements illustrated and described and other applications of them which are within the spirit and scope of the invention will occur to persons skilled in the art.

What is claimed is:

1. In combination in a wave transmission system, a tubular uni-conductor forming a closed transmission loop, four branch transmission circuits connected symmetrically thereto at spaced points around the loop, each by a series electrical connection, one of said branch transmission circuits comprising a source of signal waves of given frequency feeding into said loop, a second branch transmission circuit comprising a source of beating waves of different frequency feeding into said loop, and at least one of the two other branch transmission circuits including means for combining the portions of said signal waves and said beating waves diverted therein from said loop and means for making the relative electrical characteristics of the portions of the looped conductor connecting said four branch transmission circuits such that each of said two other branch circuits will receive part of the wave power impressed on said loop by said one or said second branch circuit and the fourth branch circuit will receive substantially none of this wave power.

2. In combination, in a wave transmission sysstem, four sections of hollow metal wave guide connected to form a continuous transmission loop, and four branch transmission circuits each comprising a straight hollow metal wave guide coplanar with the wave guide loop and respectively joined symmetrically thereto in the electric plane at a difierent one of the four junctions between the sections of wave guide therein, the opposite junctions of the transmission loop with said branch circuits having identical electrical characteristics and the opposite wave guide sections in said loop having identical electrical characteristics except for the inclusion in one of them of a suitable twist for producing a -degree phase shift in the polarity of a wave transmitted thereover with respect to the wave polarity in the other three wave guide sections, so that the two portions of a wave applied to the loop from any branch circuit, passing in opposite directions around the loop will be 180 degrees out of phase when they arrive at the point of connection of the oppositely situated branch circuit thereto.

3. The combination of claim 1, in which each of said two other branch circuits includes a wave detector for combining the applied waves from the two wave sources transmitted around the loop, and means for selecting a combination wave from the output of that detector, the selecting means of said two other branch circuits being coupled in such manner that the selected combination wave outputs of the two detectors are in proper phase relation to produce a maximum amount of wave energy of the combination wave.

4. The combination of claim 2, in which a source of signal oscillations of a given frequency is connected to one of said branch circuits so as to feed therethrough into said loop, a source of beating oscillations of different frequency is connected to another of said branch circuits so as to feed therethrough into said loop, a third one of said branch circuits includes a wave detector for combining the applied oscillations from the two oscillation sources transmitted around said loop and means for selecting a wave of a combination frequency from the output of the detector, and the fourth of said branch circuits is terminated in a suitable matching impedance.

' DOUGLAS H. RING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,750,688 Potter Mar. 18, 1930 2,147,809 Alford Feb. 21. 1939 2,416,790 Barrow Mar. 4, 1947 

